Gas separation/extraction apparatus for separating and extracting a desired gas from a gas mixture and a balance valve therefor

A gas separation/extraction apparatus comprising:

• tank means for separating and extracting a specific gas element from a gas mixture, said tank means having an suction port, an exhaust port, and adsorption means for adsorbing the gas element from the gas mixture;
• pump means having a suction port, a discharge port, a cylinder, and a piston housed in the cylinder, for alternately pressurizing and decompressing the inside of the tank means as the piston reciprocates;
• a first three-way solenoid valve connected between the exhaust port of the tank means and the suction port of the pump means;
• a second three-way solenoid valve connected between the discharge port of the pump means and the suction port of the tank means;
• and
• pressure balance means connected between the second three-way solenoid valve and the suction port of the tank means, for gradually eliminating a difference in pressure between the tank means and the pump means as the tank means is switched from a decompressed state to a pressurized state.